Polymerisable compositions

ABSTRACT

Highly filled, curable compositions containing a curable liquid, e.g. methyl methacrylate; 20 to 80% by weight of a finely divided inorganic filler of defined particle size, e.g. silica; a functionalized polymer containing a low Tg component which is soluble in the curable liquid, e.g. a functionalized vinyl aromatic/conjugated diene block copolymer; and other components which diperse the filler in the curable liquid and couple the filler to the matrix can be used to produce cured composites which show improved resistance to stress induced by thermal cycling.

This invention relates to highly filled, curable compositions suitablefor moulding shaped articles and to the articles moulded therefrom.

BACKGROUND OF THE INVENTION

Composites of highly filled polymeric compositions are becomingincreasingly used as materials of construction, particularly for kitchensinks, kitchen surfaces and sanitaryware, because of their attractiveappearance and hard wearing properties. Fluid, curable compositionscontaining high volumes of finely divided fillers suitable for formingsuch articles have been described in British Patent No. 1 493 393. Thisspecification describes fluid, curable compositions wherein high volumesof filler of specified particle size are dispersed in a curable materialusing polymeric diapersants. The use of polymeric diapersants enablecompositions to be obtained containing high volumes of finely dividedfillers, for example 50% by volume, which have a remarkably lowviscosity enabling the compositions to be readily handled for example bypumping. This low viscosity, in turn, enables the compositions to besold as fluid dispersions which can be readily transported tofabricators who can mould articles in inexpensive low pressure moulds.Although some sedimentation will inevitably occur on storage, thepolymeric diapersant maintains the filler particles in a state ofstable, deflocculation so that the segment can be readily redispersed bymild agitation to give a dispersion in which the filler particles aresubstantially uniformly dispersed and will remain so whilst thecomposition is converted from a fluid dispersion to a fully curedcomposite. The presence of the polymeric diapersant, and its function ofkeeping the particles in a state of stable deflocculation, not onlyenables a low viscosity, redispersible dispersion to be obtained, butensures that compatibility of the components is maintained as thecomposition is cured so that a cured product free from cracks and flawsis obtained.

It is also possible to fabricate moulded articles which have a viscositytoo high to be of practical value as transportable, low viscosity,redispersible compositions. Nevertheless, these compositions are usefulwhere the fabrication operation is carried out at the same location asthe composition is prepared and where storage and redispersion are not aproblem. These compositions must also contain fillers which are properlydispersed within the curable composition to avoid problems offlocculation and cracking on polymerisation.

Although these compositions are widely used in the applicationsdescribed above a small proportion of moulded articles fail prematurelyin service, when subjected to thermal cycling such as experienced by akitchen sink subjected successively to very hot and cold water. Curablecompositions have now been devised which provide moulded articles havingan improved thermal resilience, i.e. an improved performance in respectof the damage tolerance thermal shock test and often in respect of thethermal shock test, both of which are hereinafter described.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided a highlyfilled, curable composition comprising

(A) an addition polymerisable organic liquid comprising at least oneolefinically unsaturated monomer and which addition polymerisableorganic liquid on curing forms a solid polymer;

(B) 20 to 80% by volume of a finely divided particulate inorganic fillerhaving a weight average particle size of less than 50 microns but nothaving a BET surface area of more than 30 m².cm⁻³.

(C) a functionalised polymeric material soluble in the organic liquidbut which is phase separated by the time the composition has been curedand containing at least one segment of low Tg polymeric material,optionally essentially free from saturation, which exhibits a Tg of lessthan 0° C. and preferably less than -25° C.;

D) a component which is capable of associating with and effectinganchoring to the particles of the inorganic filler and which provides asufficiently large steric layer soluble in component A whereby fillerparticles are dispersed in the organic liquid; and

(E) a component which will provide chemical bonding between the fillerand polymer matrix formed by curing the polymerisable liquid.

Components C, D and E may be separate additive materials each providingthe particular specified functions. Alternatively, more than onefunction may be provided in a single material, for example a singlecomponent may provide a dispersing

DESCRIPTION OF PREFERRED EMBODIMENTS

Preferred polymerisable organic liquids (A) have a viscosity below 1,000centipoise, more preferably below 100 centipoise, as measured at ambienttemperatures using a Brookfield viscometer. Particularly preferredpolymerisable organic liquids have a viscosity of up to 50 centipoise.More particularly, the polymerisable organic liquid is one which curesto form a polymer having a glass transition temperature of at least 60°C. preferably of at least 80° C. and more preferably of at least 100° C.

Preferred polymerisable organic liquids comprise at least one monoolefinically unsaturated monomer which may be selected from any of themono olefinically unsaturated monomers known in the art.

Suitable mono olefinically unsaturated monomers may be selected from theacrylic type monomers such as acrylic, methacrylic and chloroacrylicacids (i.e. CH₂ ═CHClCO.OH), acrylamide and methacrylamide,acrylonitrile and methacrylonitrile, alkoxyalkyl acrylamides andmethacrylamides, e.g. butoxymethyl acrylamide and methoxymethylmethacrylamide, hydroxyalkyl acrylamides and methacrylamides, e.g.N-methylol acrylamide and methacrylamide, the metal acrylates andmethacrylates, and the esters of acrylic, methacrylic and chloroacrylicacids with alcohols and phenols; the vinyl aromatic compounds, e.g.styrene and substituted derivatives thereof such as the halogenatedderivates thereof and vinyl toluene; the vinyl esters, e.g. vinylacetate, and vinyl pyrrolidone.

In a preferred polymerisable organic liquid, the at least one monoolefinically unsaturated monomer is an acrylic or methacrylic acid esterhaving the formula CH₂ ═C(R)CO.ORR² where R is H or methyl, especiallymethyl, and R² is optionally substituted hydrocarbyl (e.g. optionallyhalo or hydroxy substituted hydrocarbyl) and in particular is a C₁₋₈alkyl, a C₆₋₁₀ cycloalkyl or a C₆₋₁₀ aryl group. Specific examples ofsuch monomers include the non-substituted esters of acrylic andmethacrylic acids such as methyl methacrylate, ethyl methacrylate,isopropyl methacrylate, isobutyl methacrylate, cyclohexyl methacrylate,isobornyl methacrylate, benzyl methacrylate, phenyl methacrylate andisobornyl acrylate and the substituted esters of acrylic and methacrylicacids such as hydroxyethyl methacrylate and hydroxypropyl methacrylate.More particularly, the mono olefinically unsaturated monomerincorporated in the polymerisable organic liquid is a C₁₋₈ alkyl esterof methacrylic acid. Methyl methacrylate is an especially preferredmonomer.

The polymerisable organic liquid may comprise a mixture of monoolefinically unsaturated monomers, for example a mixture of the monoolefinically unsaturated monomers specified as preferred above.

The preferred polymerisable organic liquids may also comprise at leastone polyolefinically unsaturated monomer so that the polymer which formson curing the polymerisable organic liquid is a cross-linked polymer.Suitable polyolefinically unsaturated monomers may be selected fromthose known in the art. Preferred polyolefinically unsaturated monomersare the poly(meth)acrylate esters of an organic polyol and acrylic ormethacrylic acid having the formula: ##STR1## wherein R³ is the hydroxyfree residue of an organic polyol which comprised at least two hydroxylgroups in the molecule bonded to different carbon atoms;

R⁴ and R⁵ are each independently hydrogen or methyl: and n is an integerhaving a value of at least 1, preferably a value of from 1 to 3.

Suitable poly(meth)acrylates of this type include, inter alia, themono-, di-, tri- and tetra-alkylene glycol di(meth)acrylates such as1,3-butylene glycol dimethacrylate, 1,3-butylene glycol diacrylate,ethylene glycol diacrylate, ethylene glycol dimethacrylate, triethyleneglycol diacrylate, triethylene glycol dimethacrylate and tetraethyleneglycol dimethacrylate, and the trialkylolalkane tri(meth)acrylates suchas trimethylolpropane trimethacrylate and trimethylolpropanetriacrylate. Other suitable poly(meth)acrylates may be selected from thepolyalkylene glycol di(meth)acrylates, such as polyethylene glycoldimethacrylate, the bisphenol di(meth)acrylates, such as Bisphenol Adimethacrylate, and the di(meth)acrylates of the alkoxylated bisphenols,such as the dimethacrylate of an ethoxylated and/or propoxylatedderivative of Bisphenol A. The poly(meth)acrylate monomer may also be anacrylated or methacrylated epoxy resin, for example the product derivedby reacting methacrylic acid with an epoxy resin which is the reactionproduct of a bisphenol, such ms Bisphenol A, and a halohydrin, such asepichlorohydrin. Mixtures of poly(meth)acrylate monomers may be used ifdesired.

More particularly, the poly(meth)acrylate monomer is a mono-, di-, tri-or tetra-alkylene glycol di(meth)acrylates or a trialkylolalkanetri(meth)acrylates, especially the former. A particularly preferredpoly(meth)acrylate is ethylene glycol dimethacrylate.

The polymerisable organic liquid will usually comprise (by weight) from0.2 to 20, for example from 0.5 to 20%, more usually from 0.5 to 15%,for example from 1.0 to 15%, by weight, and preferably from 0.5 to 10%for example from 1.0 to 10%, of the at least one polyolefinicallyunsaturated monomer, and usually from 99.8 to 80%, for example 99.5 to80%, more usually from 99.5 to 85%, for example 99 to 85%, andpreferably from 99.5 to 90%, for example from 99 to 90% by weight of theat least one olefinically unsaturated monomer.

However, certain polyolefinically unsaturated monomers may be employedin higher concentrations, e.g. the polyalkylene glycol di(meth)acrylatesand the di(meth)acrylates of the alkoxylated bisphenol derivatives. Apolymerisable organic liquid comprising such monomers may comprise up to70% by weight thereof, e.g. up to 50% by weight.

Suitable inorganic fillers (B) may include amphoteric, basic andsilicaceous fillers, and may be of natural or synethetic origin. Theinorganic filler, if amphoteric, may, for example, be an oxide of thistype. Suitable such inorganic fillers include oxides and hydroxides ofaluminium, including hydrated alumina. The inorganic filler, if basic,may, for example, be an oxide, a hydroxide, a carbonate or a basiccarbonate. Suitable inorganic fillers of this type include, inter alia,the oxides, hydroxides, carbonates and basic carbonates of alkalineearth metals and of zinc. Suitable silicaceous fillers include, interalia, substantially pure silica, for example sand, quartz, cristobaliteand precipitated or fused silica, or the metal silicates oraluminosilicates. Further useful inorganic fillers may be selected fromthe metal aluminates, phosphates, sulphates, sulphides and carbides.Silicaceous fillers are preferred, especially the silica fillers.

When the inorganic filler is to be used in a composition of the typedescribed in British Patent Specification 1 493 393 providing a stablydeflocculated redispersible dispersion the inorganic filler should beone in which the maximum size of any particle present is 100 microns,and at least 95% by number of the particles are of a size 10 microns orless, and where the particles have a surface area of from 30 m².cm⁻³ to1 m².cm⁻³ (approximately from 10 m².g⁻¹ to 0.4 m².g⁻¹), preferably from20 m².cm⁻³ to 2 m².cm⁻³ (approximately from 8.5 m².g⁻¹ to 0. m².g⁻¹), asdetermined by the B.E.T. nitrogen absorption method.

Preferably more than 99% by number of the particles are of a size 10microns or less, and in general the nearer the number proportion of suchparticles approaches 100% the better, e.g. a proportion of 99.999% bynumber of a size 10 microns or less gives very satisfactory results. Itis at the same time preferred that the maximum size of any particlespresent should be 75 microns, even more preferred that the maximum sizeshould be 50 microns. The inorganic filler particles for use in theinvention may have any form suitable for a filler, e.g. they may be ofgranular, fibrillar or laminar form.

In compositions having less exacting requirements, for example, wherethe composition is to be made up and cured in the same processingfacility (in-house) and where it is not necessary to provide adispersion which is readily pumpable from drums and which can beredispersed after storage, it is not necessary for the particle size tobe so critical. For such compositions the BET particle surface area maybe less than 1 m².cm⁻ 3 and, for example, the weight average particlesize may be as much as 50 microns or more. The BET particle surface areashould be less than 30 m².cm⁻³.

Curable compositions contain from 20 to 80% by volume of the finelydivided particulate inorganic filler. Preferably the concentration ofthe inorganic filler is from 30% to 75% by volume and more preferablyfrom 40 to 70% by volume of the total volume of the curable composition.

Where the inorganic filler is already available in the required particlesize, the particles of inorganic filler can be dispersed in the curablecompositions using techniques known in the art. Mixing processes such asroll milling or high shear mixing may be used to disperse the inorganicfiller. For example, the inorganic filler may be mixed with thepolymerisable organic liquid or a portion thereof to form afiller/liquid mixture into which is added the copolymer dispersant, e.g.as a solution in a component of the polymerisable organic liquid, withmixing. A further suitable technique involves blending the inorganicfiller in a component of the polymerisable organic liquid and thenblending the resulting mixture with the remaining components of thecurable composition. Alternatively, the finely divided particles may beproduced directly in the presence of the curable composition, or in aliquid component thereof, by comminution of coarse particles.Comminution of coarse material to yield smaller size particles can bereadily carried out using conventional ball mills, stirred ball mills orvibratory mills.

Where the dispersion need not be limited to a stably deflocculatedredispersible dispersion, i.e. a level of non-redispersion can betolerated, the inorganic filler used to produce curable compositions myalso comprise a coarse filler material, e.g. a filler material theparticles of which have a mean size across their largest dimension of atleast 100 microns, e.g. greater than 200 microns, and typically withinthe range 100 to b00 microns, e.g. 200 or 300 microns. Such compositionsare useful where it is required to produce a surface rich in largerfiller particles or where some special aesthetic effect such as asimulated granite effect is required.

The functionalised polymeric material (C) soluble in the organic liquid(A) containing at least one segment of low Tg polymeric material havinga Tg of less than 0° C. may consist wholly of such a low Tg polymericmaterial. Alternatively, and preferably, the functionalised polymericmaterial may contain segments of such material, for example as in ablock copolymer.

The at least one settlement of low Tg polymeric material may beessentially free from unsaturation. For example, the functionalisedpolymeric material may consist wholly of a homopolymer of 1,3 butadienewhich has been hydrogenated or, preferably, may be a block copolymerobtained from an aromatic vinyl compound and a conjugated diene compoundwhich has been selectively hydrogenated.

Functionalised versions of such polymers have been previously describedand are commercially available in several forms. Selectivelyhydrogenated block copolymers modified with acid compounds aredescribed, for example, in United States Patent Specification No.4578429 and are commercially available from Shell Oil Company as theKraton G series of polymers. United States Reissue Patent No. 27145describes the production of selectively hydrogenated vinylarene/conjugated diene block copolymers from which the functionalisedblock copolymers of U.S. Pat. No. 4 578 429 are prepared.

The term "essentially free from unsaturation" used in the presentapplication is used in the sense that the aforementioned blockcopolymers have been hydrogenated to such an extent that the originalunsaturation present has been reduced to a level at which theirsensitivity to oxidation is minimised. This is achieved according toU.S. Pat. No. Re. 27145 by reducing the unsaturation of the conjugateddiene polymer block to less than 10% of the original unsaturation.Preferably, the level of unsaturation is at an insignificant level.

The term "functionalised" used in the present application is used in thesense that the polymeric component contains, particularly as pendantgroups, moieties which my be used as bonding agents in respect to theorganic filler present in the curable composition. Preferred functionalgroups may be selected from carboxylic acid, carboxylic anhydride,hydroxyl, ester, imide, amide, amine, epoxy and acid chloride groups,carboxylic acid and anhydride being particularly preferred.

In a preferred form, the at least one segment of low Tg polymericmaterial is essentially free from unsaturation and the functional groupsare selected from carboxylic acid, carboxylic anhydride, hydroxyl,ester, imide, amide, amine, epoxy and acid chloride groups, carboxylicacid and anhydride being preferred.

Where the functionalised polymeric material also comprises polymersegments which do not have a Tg of less than 0° C. it is preferred thatthe functional groups are associated with, e.g. pendant from, the atleast one segment of low Tg polymeric material.

It is preferred that the at least one segment of low Tg polymericmaterial has a molecular weight (Mn) of at least 5000 although materialshaving a lower molecular weight are useful in improving overallproperties particularly when they include a component providing either adispersing effect or a coupling effect or both.

Suitable functionalised multi-block polymers for use as component Cinclude functionalised vinyl aromatic/conjugated diene block copolymersand selectively hydrogenated variants thereof. The polymerisedconjugated diets hydrocarbon block should preferably have an averagemolecular Weight (Mn) of at least 20,000 whereas the polymerisedmonoalkenyl aromatic hydrocarbon block should preferably have an averagemolecular weight of at least 2,000 and not more than 115,000. The weightpercentage of the monoalkenyl aromatic block in the block copolymer ispreferably less than 35% when the polymeric dispersant derived fromthese block copolymers is required to confer optimum resistance cothermal and mechanical shock.

The functionalised polymeric component C should be soluble in thepolymerisable organic liquid but should phase separate whilst thecomposition is being cured so that it forms a separate phase which ispresent in the cured article. Component C may be present in the form offinely dispersed particles having a maximum dimension in the range from0.01 microns to 5 microns but may also be present in the form of aco-continuous phase of material of irregular shape with a minimumdimension greater than 5 micron.

When it is desired to obtain a significant improvement in the damagetolerance test it is necessary that after the curing process the curedcomposition comprises the at least one segment of low Tg polymericmaterial in a noncross-linked state, thereby retaining its low Tg. It isgenerally possible to observe the presence of a low Tg component in acured moulding using dynamic mechanical thermal analysis testing (DMTA)to provide a check that the low Tg component has not been changed duringthe curing process so as to lose its rubberiness.

In a second aspect the present invention provides the use of afunctionalised polymeric material as an agent to improve the thermalresilience of a moulded article manufactured from a highly filled,curable composition comprising

(A) an addition polymerisable organic liquid comprising at least oneolefinically unsaturated monomer and which addition polymerisableorganic liquid on curing forms a solid polymer;

(B) 20 to 80% by volume of a finely divided particulate inorganic fillerhaving a weight average particle size of less than 50 microns but nothaving a BET surface area of more than 30m².cm⁻³ ;

(C) the functionalised polymeric material which is soluble in theorganic liquid but which is phase separated by the time the compositionhas been cured and containing at least one segment of low Tg polymericmaterial, optionally essentially free from unsaturation, exhibiting a Tgof less than 0° C. and preferably less than -25° C.; and optionally

(D) a component which is capable of associating with and effectinganchoring to the particles of the inorganic filler and which provides asufficiently large steric layer soluble in component A whereby fillerparticles are dispersed in the organic liquid; and/or

(E) a component which will provide chemical bonding between the fillerand polymer matrix formed by curing the polymerisable liquid.

The component D comprises an amphipathic material in the sense thatmolecules of the material contain two distinct portions, a portion whichis capable of associating with and effecting anchoring to the fillerparticles B, and a portion soluble in component A and having asufficiently large steric volume in component A to achieve dispersion ofthe filler particles in component A.

Typically useful variations of component D are expensively described inBritish Patent Specification No. 1493393. The latter describesdispersing agents which are amphipathic substances containing (a) atleast one chain-like component of molecular weight at least 500 which issolvated by the polymerisable organic liquid (A) and is also solvatedby, or is compatible with, the oligomeric or polymeric products whichresult throughout the course of the curing operation from thepolymerisable organic liquid, and (b) one or more groupings which arecapable of associating with, and effecting anchoring to the particles ofthe inorganic filler (B). The chain-like component is solvated by thepolymerisable organic liquid or its curing products in the sense that,if this component were an independent molecule, the polymerisableorganic liquid or those products would be significantly better thantheta-solvents for it; the nature of a theta-solvent is discussed in"Polymer Handbook" (ed. Brandrup and Immergut, Intersciene, 1966) and in"Principles of Polymer Chemistry, Chapters 12-14 (Flory:Cornell, 1953).More simply, the polymerisable organic liquid may be described as beinga "good" solvent for the chain-like component.

The component D may itself contain a component which will effect astrong bond between the filler particles and the matrix, i.e. couple thefiller particles and the matrix. Alternatively, a further separatecomponent, E, may be included to provide this function.

The particular type of coupling or bonding agent to be used will dependupon the nature of the inorganic filler and of the polymerisable organicliquid. Suitable bonding agents are in general substances containinggroups which can form a multiplicity of ionic, covalent or hydrogenbonds with the particle, and also groups which can react to form bondswith the polymer matrix. Suitable groups for bonding to particles havinghydroxylic, metal oxide or silicaceous surfaces are, for example, theoligomeric hydrolysis products of alkoxy silanes, chlorosilanes andalkyl titanates as well as the trivalent chromium complexes or organicacids. Where the particle surface is of a basic character, as forexample in the case of particles of alkaline earth metal carbonates orof metals such as aluminium, chromium and steel, suitable bonding groupsare carboxylic acid groups. In the case of particles with acidicsurfaces, such as those of kaolin, amine salt groups are suitable forbonding to the particles.

Groups suitable for bringing about bonding with the polymer matrix aretypically those which co-react with the polymerisable organic liquidduring the polymerisation stage. Thus an interfacial bonding agentcontaining an ethylenically unsaturated group is suitable for use withaddition polymerisation systems involving vinyl, vinylidene and similarunsaturated monomers. An agent containing an amino, an oxirane or acarboxyl group is suitable for use with epoxy-group-containingcompounds. Examples of suitable interfacial bonding agents include:

gamma-methacryloxypropyl trimethoxy silane

gamma-aminopropyl trimethoxysilane

gamma-glycidyl oxypropyl trimethoxysilane

vinyl triathoxysilane

vinyl triacetoxysilane

vinyl trichlorosilane

Acrylic and methacrylic acids and their metal salts

Methacrylatochromic chloride

Maleimidopropionic acid

Succinimidopropionic acid

4-Amonimethylpiperidine

Tetraisopropyl and tetrabutyl titanates

The amounts of the interfacial bonding agent used are, in general thoseconventional in the art of polymeric materials reinforced with inorganicfillers. A suitable minimum usage for most applications is 0.001 g ofbonding agent per square meter of filler particle surface area. Ifdesired, a mixture of two or more interfacial bonding agents of thetypes described may be used.

Curable compositions may also comprise one or more preformed polymerswhich may be in solution in the polymerisable organic liquid, forexample, a partially polymerised syrup of the polymerisable organicliquid. Alternatively they may be present in a state of dispersiontherein. Preformed polymers may also be included as a thickening aid toadjust the viscosity of the curable compositions.

Curable compositions may also comprise any of the additives that areconventionally used in curable moulding compositions such as pigments,dyestuffs, mould release agents and polymerisation inhibitors.

Curable compositions are useful employed in the manufacture of mouldedarticles. Fluid curable compositions having a low viscosity obtainableusing the dispersants of the invention are particularly suitable formoulding applications and, accordingly preferred curable compositionswill have a viscosity, as measured when the filler is dispersed in thepolymerisable organic liquid, of less than 5000 centipoise at ambienttemperatures. More particularly, compositions having a viscosity, asmeasured when the filler is so dispersed, in the range of from 50 to2000 centipoise and especially in the range of from 50 to 1000centipoise are preferred.

In a third aspect of the present invention there is provided a mouldedarticle formed by curing the curable composition of the first aspect ofthe invention.

Moulded articles may be fabricated using techniques conventional in theart. For example, the curable composition can be cast into a mould andthen in-mould polymerised using a suitable catalyst to initiate thepolymerisation reaction.

The polymerisable compositions may be cured in accordance withtechniques conventional in the art of free radical additionpolymerisation. The polymerisation may be initiated by a wide range ofcatalysts, but it is preferred to use a heat activated catalyst,particularly one which is activated at temperatures of from 30° to 120°C. The catalyst is preferably added immediately prior to curing thecompositions; this may be particularily important where the catalyst isactivated at temperatures below or around ambient. Suitable catalystsare well known to those skilled in the art and may include, for example,organic peroxides, such as dibenzoyl peroxide, diocatanoyl peroxide anddi-t-butyl peroxide, which may be used in conjunction with an amineaccelerator, e.g. N,N-diethylaniline or N,N-dimethyl-para-toluidine; thehydroperoxides, such as t-butyl hydroperoxide; the peroxydicarbonates,such as diisopropylperoxydicarbonate, di-n-propylperoxydicarbonate,di-(2-ethoxyethyl)-peroxydicarbonate,di-(methoxyisopropyl)-peroxydicarbonate,di-(2-ethylhexyl)-peroxydicarbonate andbis(4-t-butylcylcohexyl)peroxydicarbonate; and the peresters. The mostpreferred catalysts are the peroxydicarbonates. The catalyst isconveniently used in an mount ranging from 0.1% to 3.5% by weight basedon the total weight of the polymerisable organic liquid.

It may be desirable during the filling of the mould to maintain thetemperature of the mould surfaces below the temperature at which thecatalyst is activated, so as to prevent premature polymerisation andgelation.

Prior to moulding, the internal mould surfaces may be coated with arelease agent to prevent adhesion of the cured materials to the mouldand to obtain a good surface finish. These polytetrafluoroethylene,silicone and polyvinylalcohol techniques are well known in the art.Examples of suitable external mould release agents include, inter alia,

After the in-mould polymerisation is complete, the filled polymericarticle may be subjected to an in-mould post-curing process, after whichit is demoulded, or, alternatively, it may be demoulded immediately andthen optionally subjected to a post-curing process.

The invention is further illustrated by reference to the followingexamples.

EXAMPLE 1

The following ingredients were mixed in a 25 liter drum and rolled atapproximately 30 rpm for 24 hours.

    ______________________________________                                        Methyl methacrylate       7.43   kg                                           Ethylene glycol dimethacrylate                                                                          0.092  kg                                           Kraton FG1901X (a maleinised ethylene/                                                                  0.92   kg                                           butylene-styrene block copolymer available                                    from the Shell Chemical Company)                                              Polymeric dispersant (95:5 methyl                                                                       0.22   kg                                           methacrylate/dimethylamino ethyl                                              methacrylate, Mw 50,000 (GPC)                                                 3-(trimethoxysilyl)propylmethacrylate                                                                   0.088  kg                                           Stearic acid              0.045  kg                                           Cristobalite silica (mean weight                                                                        22     kg                                           average particle size 10 microns)                                             ______________________________________                                    

A free flowing dispersion having a viscosity 300 centipoise measured ona Brookfield viscometer using a No. 3 spindle at 30 rpm.

The dispersion was cured in the form of plaques (dimensions 300 mm×300mm×5 mm) and kitchen sinks after catalysing with 0.6% by weight of thedispersion of Perkadex 16 catalyst(bis(4-t-butyl-cyclohexyl)peroxydicarbonate) (obtainable from Akzo)using the appropriate moulds. The curing cycle for moulding plaques was30 minutes at 60° C. followed by 45 minutes at 90° C. The curing cyclefor moulding sinks was 80° C. on show face and 50° C. on back face for15 minutes, followed by 100° C. on show face and 100° C. on back facefor 15 minutes, the moulding pressure was held an 2 bar for 10 minutesfollowed by 4.5 bar for 20 minutes.

The plaques were cut into test pieces for measurement of modulus,failure stress, failure strain and impact strength. The test methodswere three point bend flexural test, ASTMD790-71 and the Charpyunnotched impact test, ASTM D256 Method B.

The values measured are recorded below:

    ______________________________________                                        Modulus           GPa      10.6                                               Failure Stress    MPa      103                                                Failure Strain    %        2.2                                                Impact Strength   kJ · m.sup.-2                                                                 8.3                                                ______________________________________                                    

The thermal shock performance of the moulded sinks were assessed by thefollowing method. Hot and cold water were alternately, and repeatedly,jetted onto the base of the sink: the sink was continually observed andthe number of cycles to failure or damage was measured. Each heating andcooling cycle was as follows: hot water at 93° C.±2° C. was jetted ontothe base of the sink for 90 seconds, followed by a dwell time of 30seconds during which time there was no flow of water, then cold water15° C.± was jetted onto the base of the sink for 90 seconds, followed bya further dwell time of 30 seconds.

The damage tolerance thermal shock test involved using the same heatingand cooling cycle described above, but the sink was scratched by drawinga device in which a `Stanley Knife Blade` was protruding by 1 mm from aflat surface across the show surface of the base of the sink. A scratchof length 2.5 cm was made at the point of impingement of the water jet.The sinks were observed during the thermal cycling and cycles to failureor damage were recorded.

In the damage tolerance thermal shock test minor damage was observed at180 cycles, and failure occurred at 360 cycles.

Comparative Example A

The following ingredients were mixed into 25 liter drums and rolled atapproximately 30 rpm for 24 hours.

    ______________________________________                                        Methyl methacrylate        8.03   kg                                          Ethylene glycol dimethacrylate                                                                           0.092  kg                                          Polymeric dispersant (95:5 methyl                                                                        0.21   kg                                          methacrylate dimethylamino ethyl                                              methacrylate, Mw 50,000 (GPC)                                                 Polymethyl methacrylate Mw 500,000 (GPC)                                                                 0.18   kg                                          Stearic acid               0.045  kg                                          Cristobalite silica as used in Example 1                                                                 22     kg                                          ______________________________________                                    

A free flowing dispersion was obtained having a viscosity of 410centipoise measured by the method described in Example 1.

The dispersions were moulded and cured into a plaque and sinks asdescribed in Example 1. The plaque was cut into specimens for mechanicalproperty determination as described in Example 1. The values measuredare recorded below:

    ______________________________________                                        Modulus           GPa      12.8                                               Failure Stress    MPa      64                                                 Failure Strain    %        0.5                                                Impact Strength   kJ · m.sup.-2                                                                 2.0                                                ______________________________________                                    

Sinks were tested in the thermal shock test and failed on average (4tests) after 90 cycles.

In the damage tolerance thermal shock test no minor damage was observedbefore catastrophic failure at 30 cycles.

Comparative Example B

The following ingredients were mixed into 25 liter drums and rolled atapproximately 30 rpm for 24 hours.

    ______________________________________                                        Methyl methacrylate      8.03    kg                                           Ethylene glycol dimethacrylate                                                                         0.092   kg                                           Polymeric dispersant (95:5 methyl                                                                      0.21    kg                                           methacrylate : dimethylamino                                                  ethyl methacrylate, Mw 50,000 (GPC)                                           Polymethyl methacrylate Mw 500,000 (GPC)                                                               0.18    kg                                           3-(trimethoxysilyl)propylmethacrylate                                                                  0.022   kg                                           Stearic acid             0.045   kg                                           Cristobalite silica as used in Example 1                                                               22      kg                                           ______________________________________                                    

A free flowing dispersion was obtained having a viscosity of 410centipoise measured by the method described in Example 1.

The dispersions were moulded and cured into a plaque and sinks asdescribed in Example 1. The plaque was cut into specimens for mechanicalproperty determination as described in Example 1. The values measuredare recorded below.

    ______________________________________                                        Modulus           GPa      12.5                                               Failure Stress    MPa      115                                                Failure Strain    %        1.0                                                Impact Strength   kJ · m.sup.-2                                                                 5.0                                                ______________________________________                                    

Sinks were tested in the thermal shock test and failed on average (>25tests) after 700 cycles.

In the damage tolerance thermal shock test no minor damage was observedbefore catastrophic failure occurred at 30 cycles.

EXAMPLE 2

The procedure of Example 1 was followed using a composition of thefollowing ingredients:

    ______________________________________                                        Methyl methacrylate      7.45   kg                                            Ethylene glycol dimethacrylate                                                                         0.092  kg                                            Kraton FG1901X           0.92   kg                                            3-(trimethoxysilyl)propylmethacrylate                                                                  0.088  kg                                            Stearic acid             0.045  kg                                            Cristobalite silica as used in                                                                         22     kg                                            Example 4 or 1                                                                ______________________________________                                    

A free flowing dispersion was obtained, the viscosity measured by themethod described in Example 1 was found to rise from 350 centipoise to1020 centipoise over 7 days.

The following properties were measured using the test methods describedin Example 1 on samples cut from moulded plaques:

    ______________________________________                                        Modulus           GPa      10.0                                               Failure Stress    MPa      95                                                 Failure Strain    %        2.0                                                Impact Strength   kJ · m.sup.-2                                                                 6.3                                                ______________________________________                                    

Sinks were tested in the damage tolerance thermal shock test, minordamage was observed at 231 cycles, and failure occurred at 464 cycles.

Comparative Example C

The procedure of Example 1 was followed using a composition containing anon-functionalised soluble polymeric material and with the followingingredients:

    ______________________________________                                        Methyl methacrylate      7.55   kg                                            Ethylene glycol dimethacrylate                                                                         0.092  kg                                            Kraton DX1300            0.61   kg                                            a styrene/butadiene/styrene block                                             copolymer available from the Shell                                            Chemical Company                                                              Polymeric dispersant (95:5 methyl                                                                      0.22   kg                                            methacrylate/dimethylamino ethyl                                              methacrylate, Mw 50,000 (GPC)                                                 3-(trimethoxysilyl)propylmethacrylate                                                                  0.088  kg                                            Stearic acid             0.045  kg                                            Cristobalite silica as used in Example 1                                                               22     kg                                            ______________________________________                                    

A free flowing dispersion having a viscosity of 470 centipoise measuredby the method described in Example 1 was obtained.

The following properties were measured on plaques and sinks moulded fromthis dispersion using the test methods described in Example 1 on samplescut from moulded plaques:

    ______________________________________                                        Modulus           GPa      10.2                                               Failure Stress    MPa      126                                                Failure Strain    %        1.8                                                Impact Strength   kJ · m.sup.-2                                                                 5.2                                                ______________________________________                                    

In the damage tolerance thermal shock test no minor damage was observedbefore catastrophic failure occurred at 61 cycles.

Comparative Example D

The following ingredients were mixed into 25 liter drums and rolled atapproximately 30 rpm for 24 hours.

    ______________________________________                                        Methyl methacrylate      8.72   kg                                            Ethylene glycol dimethacrylate                                                                         0.08   kg                                            Kraton G-1652            0.69   kg                                            a styrene/ethylene/butadiene/styrene                                          block copolymer available from the                                            Shell Chemical Company                                                        Polymeric dispersant (95:5 methyl                                                                      0.20   kg                                            methacrylate : dimethylamino ethyl                                            methacrylate, Mw 50,000 (GPC)                                                 3-(trimethoxysilyl)propylmethacrylate                                                                  0.080  kg                                            Stearic acid             0.045  kg                                            Cristobalite silica as used in Example 1                                                               20     kg                                            ______________________________________                                    

A free flowing dispersion was obtained having a vosocisity of 760centipoise measured by the method described in Example 1.

The dispersions were moulded and poured into a plaque and sinks asdescribed in Example 1. The plaque was cut into specimens for mechanicalproperty determination as described in Example 1. The values measuredare recorded below:

    ______________________________________                                        Modulus           GPa      11.2                                               Failure Stress    MPa      101                                                Failure Strain    %        1.3                                                Impact Strength   kJ · m.sup.-2                                                                 5.0                                                ______________________________________                                    

In the damage tolerance thermal shock test minor damage was observed at143 cycles, and failure occurred at 266 cycles.

EXAMPLE 3

The following ingredients were mixed in a 1 liter glass bottle androlled at approximately 30 rpm for 24 hours:

    ______________________________________                                        Methyl methacrylate       216.2   g                                           Ethylene glycol dimethacrylate                                                                          2.2     9                                           Kraton FG1901X            22.2    g                                           3-(trimethoxysilyl)propylmethacrylate                                                                   0.15    g                                           Aluminium hydroxide, Grade C308 of Sumitomo                                                             500     9                                           having a weight average particle size                                         of 8 microns                                                                  ______________________________________                                    

A free flowing dispersion was obtained, the viscosity was 150 centipoisemeasured by the method described in Example 1.

The following properties were measured using the test methods describedin Example 1 on samples cut from moulded plaques:

    ______________________________________                                        Failure Strain    %        2.6                                                Impact Strength   kJ · m.sup.-2                                                                 6.9                                                ______________________________________                                    

Comparative Example E

The following ingredients were mixed in a 1 liter bottle and rolled atapproximately 30 rpm for 24 hours.

    ______________________________________                                        Methyl methacrylate      216.2  g                                             Ethylene glycol dimethacrylate                                                                         2.2    g                                             Polymeric dispersant (95:5 methyl                                                                      1.85   g                                             methacrylate/dimethylamino ethyl                                              methacrylate, Mw 50,000 (GPC))                                                3-(trimethoxysilyl)propylmethacrylate                                                                  0.15   g                                             Aluminum hydroxide, Grade C308 of                                                                      500    g                                             Sumitomo having a weight average                                              particle size of 8 microns.                                                   ______________________________________                                    

A free flowing dispersion was obtained the viscosity was 130 centipoisemeasured by the method described in Example 1.

The following properties were measured using the test methods describedin Example 1 on samples cut from moulded plaques:

    ______________________________________                                        Failure Strain    %        1.0                                                Impact Strength   kJ · m.sup.-2                                                                 2.7                                                ______________________________________                                    

Comparative Example F

A silylated polybutadiene was prepared by hydrosilylation of apolybutadiene of molecular weight 8000. 10 g of this product wasdissolved in 130 g of the silica used in Example 1. After 30 minutesrolling the viscosity was greater than 10,000 centipoise as measured bythe method described in Example 4. This procedure was repeated using asilylated polybutadiene available from Dynamit Nobel under productnumber PS076.5. After 30 minutes of rolling the mixture had a viscositygreater than 10,000 centipoise.

We claim:
 1. A filled, curable composition comprising(A) an additionpolymerisable organic liquid which on curing forms a solid polymer; (B)20 to 80% by volume, based on the composition volume, of a finelydivided inorganic particulate filler having a weight average particlesize of less than 50 microns but not having a BET surface area of morethan 30 m².cm⁻³ ; (C) a functionalised polymeric material soluble in theorganic liquid but which is phase separated by the time the compositionhas been cured and containing at least one segment of low Tg polymericmaterial which exhibits a Tg of less than 0° C.; (D) a component whichis capable of associating with and effecting anchoring to the particlesof the inorganic filler and which provides a steric volume soluble incomponent A whereby filler particles are dispersed in the organicliquid; and (E) a component which will provide chemical bonding betweenthe filler and polymer matrix formed by curing the polymerisable organicliquid.
 2. A curable composition as claimed in claim 1 wherein thepolymerisable organic liquid (A) is one which cures to form a solidpolymer having a glass transition temperature of at least 60° C.
 3. Acurable composition as claimed in either claim 1 or claim 2 wherein thepolymerisable organic liquid (A) comprises at least one monoolefinically unsaturated monomer which is an acrylic or methacrylic acidester having the formula CH₂ ═C(R)CO.OR² where R is H or methyl and R²is unsubstituted hydrocarbyl or hydrocarbyl substituted with halogen orhydroxyl.
 4. A curable composition as claimed in claim 3 wherein thepolymerisable organic liquid (A) comprises at least one polyolefinicallyunsaturated monomer so that the polymer which forms on curing thepolymerisable organic liquid is a cross-linked polymer.
 5. A curablecomposition as claimed in claim 4 wherein the least one polyolefinicallyunsaturated monomer is a poly(meth)acrylate ester of an organic polyoland (meth)acrylic acid having the formula: ##STR2## wherein R³ is thehydroxy free residue of an organic polyol which comprised at least twohydroxyl groups in the molecule bonded to different carbon atoms;R⁴ andR⁵ are each independently hydrogen or methyl; and n is an integer havinga value of at least 1, preferably a value of from 1 to
 3. 6. A curablecomposition as claimed in claim 5 wherein the polymerisable organicliquid (A) comprises from 0.2 to 20% by weight of the at least onepolyolefinically unsaturated monomer and from 99.8 to 80% by weight ofthe at least one mono olefinically unsaturated monomer.
 7. A curablecomposition as claimed in claim 6 wherein the inorganic filler (B) is atleast one amphoteric, basic or silicaceous filler.
 8. A curablecomposition as claimed in claim 7 wherein the inorganic filler furthercomprises a coarse filler material.
 9. A curable composition as claimedin claim 8 wherein the at least one segment of low Tg polymeric materialis essentially free from unsaturation and the functional groups areselected from carboxylic acid, carboxylic anhydride, hydroxyl, ester,imide, amide, amine, epoxy and acid chloride groups.
 10. A curablecomposition as claimed in claim 9 wherein the functionalised polymericmaterial comprises polymer segments which do not have a Tg of less than0° C. and the functional groups are pendant from the at least onesegment of low Tg polymeric material.
 11. A curable composition asclaimed in claim 10 wherein the at least one segment of low Tg polymericmaterial has a molecular weight (Mn) of at least
 5000. 12. A curablecomposition as claimed in claim 11 wherein the functionalised polymericmaterial is a functionalised vinyl aromatic/conjugated diene blockcopolymer.
 13. A curable composition as claimed in claim 12 wherein thefunctionalised polymeric material is in the form of finely dispersedparticles having a maximum dimension from 0.01 microns to 5 microns. 14.A curable composition as claimed in claim 12 wherein the functionalisedpolymeric material is in the form of a co-continuous phase of materialof irregular shape with a minimum dimension greater than 5 microns. 15.A curable composition as claimed in claim 14 wherein the component (D)also contains a component which can effect a chemical bond between theinorganic filler and a polymer matrix formed by curing the polymerisableorganic liquid.
 16. A filled, curable composition comprising(A) anaddition polymerisable organic liquid comprising a mixture of methylmethacrylate and ethylene glycol dimethacrylate; (B) a finely dividedinorganic particulate filler comprising cristobalite silica having aweight average particle size of less than 50 microns but not having aBET surface area of more than 30 m².cm³ ; (C) a functionalised polymericmaterial soluble in the organic liquid but which is phase separated bythe time the composition has been cured and containing at least onesegment of low Tg polymeric material which exhibits a Tg of less than 0°C., and comprising a functionalised vinyl aromatic/conjugated dieneblock copolymer; (D) 3-(trimethoxysilyl)propylmethacrylate.
 17. A curedcomposition prepared from a curable composition as claimed in claim 16.18. A cured composition as claimed in claim 16 wherein at least some ofthe at least one segment of low Tg polymeric material is present in anoncross-linked state.
 19. A moulded article of improved thermalresilience, said article being made from a filled, curable compositioncomprising(A) an addition polymerisable organic liquid which on curingforms a solid polymer; (B) 20 to 80% by volume, based on the thecomposition volume, of a finely divided inorganic particulate fillerhaving a weight average particle size of less than 50 microns but nothaving a BET surface area of more than 30 m².cm⁻³ ; (C) a functionalisedpolymeric material soluble in the organic liquid but which is phaseseparated by the time the composition has been cured and containing atleast one segment of low Tg polymeric material exhibiting a Tg of lessthan 0° C.; and optionally (D) a component which is capable ofassociating with and effecting anchoring to the particles of theinorganic filler and which provides a steric volume soluble in componentA whereby filler particles are dispersed in the organic liquid; and/or(E) a component which will provide chemical bonding between the fillerand polymer matrix formed by curing the polymerisable organic liquid.